Optical signals

ABSTRACT

Examples disclosed herein relate, in one aspect to a method. The method may include determining an input bandwidth capacity of a network device comprising a network device port coupled to a plurality of computing devices; based on the input bandwidth capacity; generating a management signal, the management signal indicating a set of output lanes for each of the plurality of computing devices and indicating a different wavelength for each of the set of output lanes of each of a plurality of computing devices; sending the management signal to the plurality of computing devices through an optical bus; and receiving, through the optical bus, an optical signal comprising, for each computing device, a set of output signals from the set of output lanes indicated by the management signal, each output signal being represented by a wavelength indicated by the management signal.

BACKGROUND

A network device, such as an edge network switch in a datacenter, may beused to transfer data between a first set of computing devices (e.g.,downstream servers) and a second set of computing devices (e.g., anothernetwork switch), in some cases, the total amount of bandwidth from thefirst set of devices may exceed the available bandwidth between thenetwork device and the second set of devices, in which case the networkdevice is said to be over-subscribed.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description references the drawings, wherein:

FIGS. 1A-1C show examples of a network system;

FIGS. 2A-2D show other examples of the network system;

FIGS. 3A-3E show yet other examples of the network system; and

FIG. 4 shows a flowchart of an example method.

DETAILED DESCRIPTION

As mentioned above, a network device may sometimes be over-subscribed,for example, when its downstream bandwidth exceeds its upstreambandwidth capacity, limiting downstream bandwidth from devices connectedto the network device vis dedicated connections of fixed bandwidth, suchas multi-fiber push-on (MPO) cables, will cause many downstreamconnections to be unused or underutilized. For example, a downstreamcomputing device often may not need the full bandwidth of the networkdevice port to which it is connected, but any available bandwidth atthat network device port may be stranded, i.e., unusable by othercomputing devices connected to other network device ports. Strandedbandwidth on multiple network ports may force the network administratorto add additional network devices to meet the total bandwidthrequirement of the system (e.g., a datacenter), causing inefficient useof system resources such as power, end increasing overall system cost.

Examples disclosed herein describe, among other things, a network devicethat includes a network device port. The network device port may becoupled to a plurality of computing devices via an optical bus. Thenetwork device may obtain, by the network port, a plurality ofelectrical output signals from the network device, and produce, by thenetwork port, an optical output signal representing a management signaland the plurality of electrical output signals, where the managementsignal and the plurality of output signals may foe represented in theoptical output signal by different wavelengths, and where the managementsignal may select a set of output lanes from a plurality of output lanesof each of the plurality of computing devices, and assign wavelength toeach of the set of output lanes. The network device may also provide, bythe network device port, the optical output signal to each of theplurality of computing devices through the optical bus; and receive, bythe network port, through the optical bus, an optical input signalcomprising, for each computing device, a set of output signals from theset of output lanes selected by the management signal, each outputsignal being represented by a wavelengths assigned by the managementsignal.

Thus, examples disclosed herein may enable sharing of bandwidth of anetwork device port by multiple computing devices via optical componentsand cables. As discussed above, this may reduce the total number offibers network devices and/or device ports and the number of fibers usedfor connecting the computing devices to the network device, therebyreducing the overall system complexly, power consumption, cost, etc. Forexample, in some examples illustrated below, the number of computingdevices that the same network device may support is increased by afactor of four, and the number of long optical fibers connectingcomputing devices to the network device may is decreased by a factor of24 (e.g., twelve-fiber cables connecting each computing device arereplaced with one two-fiber cable shared by four computing devices). Inaddition, in some examples discussed herein, the maximum bandwidth ofeach computing device may be increased (e.g., by a factor of four),which provides additional flexibility in bandwidth allocation among aplurality of computing devices and further increasing the resourceutilization of the system.

FIG. 1A is a block diagram of an example network system 100. System 100may include among other things, a network device 150 that may becommunicatively coupled, through a network device port (e.g., 152-A) toa set of one or more computing devices 110 (e.g., 110-A, 110-B, 110-C,110-D). Two devices are said to be communicatively coupled, for example,when they can exchange information to communicate via physical ports.Port 152-B may be communicatively coupled to additional computingdevices, not shown for brevity. In some examples, network device ports152-A and 152-B may be downstream ports, and network device 150 mayinclude additional downstream ports, as well as upstream ports throughwhich network device 150 may be communicatively coupled to other networkor computing devices, not shown for brevity.

Computing device 110 may be any type of electronic device or acombination of electronic devices capable of communicating with networkdevice 150 as described below. For example, computing device 110 may beany type of a server (e.g., a blade server, a rack server, and thelike), a network switch, a router, a desktop computer, and the like. Insome examples, a number of computing devices 110 may be enclosed in anenclosure such as a server rack. Each computing device 110 may includeone or more communication ports 112 through which computing device 100may communicate with network device 150.

Network device 150 may also be any type of electronic device or acombination of electronic devices capable of communicating with the setof one or more computing devices 110. For example, network device 150may be a network switch, a router, a server, a desktop computer, and thelike. As mentioned above, network device 150 may be also connected to anumber of network devices (e.g., network switches) and/or a number ofcomputing devices (e.g., servers) on the upstream side, not shown inFIG. 1A for brevity. Network device 150 may transfer data from theupstream devices to the downstream devices (e.g., computing devices 110)and vice versa. As also discussed above, in some examples, networkdevice 150 may be over-subscribed, moaning that the required downstreambandwidth may exceed the upstream bandwidth capacity.

In some examples, each computing device 110 may be communicativelycoupled to network device 150 via a first optical waveguide 171 and asecond optical waveguide 172. For example, as illustrated in FIG. 1A,computing devices 110-A, 110-B, 110-C, and 110-D may be connected tonetwork device 150 via the following pairs of optical waveguides: 171-Aand 172-A, 171-B and 172-B, 171-C and 172-C, and 171-D and 172-D,respectively. Each optical waveguide 171 and 172 may be a single opticalfiber of any type, a polymer waveguide, and the like. In some examples,a pair of optical fibers 171 and 172 may be parts of the same opticalcable, such as a two-fiber Lucent Connector (LC) duplex cable.

In some examples, a plurality of computing devices 110 (e.g., 110-A,110-B, 110-C, and 110-D) may be coupled to the same port 152 (e.g.,152-A) of network device 150, thereby freeing other ports (e.g., 152-B)for other connections and thus increasing the number of downstreamdevices that can be support by network device 150 having a certainnumber of ports. In the example of FIG. 1A, each computing device 110 iscoupled via a corresponding pair of optical waveguides 171 and 172 toport 152-A via an optical connector 153. In some examples, port 152 mayconvert any optical signals received from computing devices 110 throughwaveguides 171-A, 171-B, 171-C, and 171-D into electrical signals, andprovide the electrical signals to lanes L0-L3. Specifically, theelectrical signals may be provided to the inputs of lanes L0-L3,indicated in FIG. 1A as input lanes L0 _(i)-L3 _(i). Similarly, port 152may convert any electrical signals obtained at outputs of lanes L0-L3(indicated as output lanes L0 _(o)-L3 _(o)) into optical signals, andprovide the optical signals into optical waveguides 172-A, 172-B, 172-C,and 172-D.

In some examples, each computing device 110 may include a communicationport 112. Port 112 may be coupled to optical waveguides 171 and 172through an optical connector 113 shown in FIG. 1C, but not shown in FIG.1A for brevity. Port 112 may convert any optical signals received fromnetwork device 150 through optical waveguides 172-A, 172-B, 172-C, and172-D into electrical signals, and pass the electrical signals to inputlanes L0 _(i)-L3 _(i)). Similarly, port 112 may convert any electricalsignals obtained at output lanes L0 _(o)-L3 _(o) into optical signals,and pass the optical signals into optical waveguides 171-A, 171-B,171-C, and 171-D.

In some examples, computing device 110 may include, among other things,a lane switch 115, a multiplexer 116, and a demultiplexer 117, Laneswitch 115 may in some examples be a part of an optical receiver,transmitter, or transceiver included in computing device 110. Laneswitch 115 may obtain one of a plurality of electrical signals at outputlanes L0 _(o)-L3 _(o) from other components (e.g., a processor, amemory, or other modules) of computing device 110, selectively convertthe electrical signal into an optical signal associated with (e.g.,modulated using) a particular wavelength (e.g., one of predefinedwavelengths λ1, λ2, λ3, and λ4), and selectively route the opticalsignal to one of a plurality of outputs of lane switch 115 connected toone of a plurality of inputs of multiplexer 116, where signalsassociated with different wavelengths may be routed to different outputsof lane switch 116 and inputs of multiplexer 116. Thus, each output oflane switch 115 (and the corresponding input of multiplexer 118) may beassociated with a different wavelength. Similarly, lane switch 116 mayobtain a plurality of optical signals from demultiplexer 117, convertthe optical signals into electrical signals, and selectively route eachelectrical signal to one of a plurality of input lanes L0 _(i)-L3 _(i)that may be connected to other components (e.g., a processor, a memory,or other modules) of computing device 110.

Multiplexer 116 may be any type of optical multiplexer, in someexamples, multiplexer 116 may receive a plurality of optical signalsfrom lane switch 115, select a set of zero, one, or more signals fromthe plural sly of optical signals, and provide the set of selectedsignals to the output of multiplexer 116, which may be coupled (e.g.,via connector 113) to optical waveguide 171. In some examples, ifmultiplexer receives two or more optical signals with differentwavelengths, multiplexer 116 may provide to waveguide 171 optical signalthat represents each of the signals, where each signal may be associatedwith a different wavelength (e.g., filtered by a different bandpassfilter). That is, multiplexer 116 may perform wave-division multiplexing(WDM) to provide into waveguide 171 an optical signal that combines aplurality of optical signals having different wavelengths into a singleoptical signal comprising each of the plurality of optical signals.

Demultiplexer 117 may be any type of optical demultiplexer. The input ofdemultiplexer 117 may be coupled (e.g., via connector 113) to opticalwaveguide 172, through which demultiplexer 117 may receive one or moresignals from network device 150. The received signals may includemanagement signals (discussed in more detail below) and data signals. Insome examples, each signal received by demultiplexer 117 from waveguide172 may be associated with a different wavelength. Demultiplexer 117 mayextract each optical signal having different wavelength from waveguide172 and provide each extracted optical serial at one of the outputs ofdemultiplexer 117. In some examples, each output or demultiplexer 117may be associated with one of a plurality of predefined wavelength(e.g., λ1, λ2, λ3 and λ4) and demultiplexer 117 may provide eachextracted signal at the output associated with the same wavelength asthe extracted signal. In some examples, the outputs of demultiplexer 117may be coupled to inputs of lane switch 115, which may selectively routeeach outputs of demultiplexer 117 to one of the input lanes L0 _(i)-L3_(i) connected to other components (e.g., a processor, a memory, orother modules) within computing device 110.

In some examples, each computing device 110 may receive from networkdevice 150 a management signal representing management data. In someexamples, the management signal may be received by computing device 110through optical waveguide 172, in some examples, the management signalmay be associated with (e.g., filtered with) a predefined wavelength(e.g., one of wavelengths λ1, λ2, λ3 or λ4, or another dedicatedwavelength), and demultiplexer 117 may extract the management signalfrom the optical signal, and pass the management signal to lane switch115, and/or any other components of computing device 110 that may becontrolled by the management signal. Thus, the management signal may beused to control lane switch 115, multiplexer 116, or other components(e.g., management processor of computing device 110, not shown forbrevity) controlling lane switch 115 and multiplexor 116, in order todynamically select the routing, selection, and wavelength assignments tovarious Input and output signals in computing device 110, as discussedin various examples provided herein.

In some examples, the management signal may indicate which of theplurality of output signals obtained at output lanes L0 _(o)-L3 _(o), ifany, may be transmitted by computing device 110 to network device 150through optical waveguide 171. In some examples, the management signalmay also indicate which wavelength (e.g., λ1, λ2, λ3 or λ4) is to beassigned to each transmitted signal. In some examples, the managementsignal may also indicate which optical signals (data signals and/ormanagement signals) received by computing device 110 through waveguide172, if any, are directed to the particular computing device 110, and towhich input lanes L0 _(i)-L3 _(i) such signal should be provided. Insome examples, lane switch 115 may route input and output signals to andfrom multiplexer 116 and demultiplexer 117 in accordance with themanagement signal, and multiplexer 116 may select its inputs inaccordance with the management signal. Thus, network device 150 may usemanagement signals to control which signals are obtained from whichcomputing device 110 and using which wavelengths. It is appreciated thatin some examples, lane switch 115, multiplexer 118, and/or demultiplexer117 may be omitted from computing device 110, and some of the routing,selection, and filtering functionality described above may be hardwiredand may be independent of the management signal.

In the example illustrated in FIG. 18, network device 150 configurescomputing devices 110-A, 110-B, 110-C, and 110-D (e.g., using themanagement signal) to transmit signals obtained at output lane L0 _(o)and to associate those signals with wavelengths λ4, λ3, λ2, and λ1,respectively. Network device 150 further configures computing devices110-A, 110-B, 110-C, and 110-D to route input signals associated withwavelengths λ4, λ3, λ2, and λ1, respectively, to input lane L0 _(i), andto discard all other input signals.

FIG. 1C further illustrates system 100 in accordance with some examples.As illustrated in FIG. 1C, each computing device 110 may be coupled tonetwork device 150 via an optical cable (e.g., an LC duplex cable) thatincludes both optical waveguides 171 and 172, The optical cable mayconnect each computing device 110 to network device 150, e.g., byoptically coupling connectors 113 (e.g., 113-A, 113-B, 113-C, and 113-D)to connector 153 (e.g., 153-A), where connectors 113 may be, forexample, two-fiber LC connectors.

FIG. 2A shows another block diagram of an example system 100. In theexample of FIG. 2A, each computing device 110 is coupled to networkdevice 150 through an optical bus 170. As illustrated in FIG. 2A,optical bus 170 may in some examples be coupled to each computing device110 via optical waveguides 171 and 172. Optical bus 170 may also becoupled to a multiplexer 158 and to a demultiplexer 157. Multiplexer 158may, in some examples, be similar to multiplexer 116. Accordingly,multiplexer 158 may receive a plurality of optical signals from networkdevice 150, select a set of zero, one, or more signals from theplurality of optical signals, and output a signal representing the setof signals, where each selected signal may be and represented by orassociated with a different wavelength, such as a predefined wavelengthassociated with the input at which the selected signal was received.

Demultiplexer 157 may, in some examples, be similar to demultiplexer117. Accordingly, demultiplexer 157 may receive from bus 170 an opticalsignal representing plurality of signals, each signal being representedby or associated with a different wavelength. Demultiplexer 157 mayextract each signal of the plurality of signals from the receivedoptical signal, and provide each extracted signal at the output ofdemultiplexer 157 that is associated with the same wavelength as theextracted signal.

Multiplexer 156 and demultiplexer 157 may be parts of separate modulesor devices, or they may be integrated into a single optical module 154.In some examples, module 154 may be attachable to, pluggable into, orotherwise coupled to connector 153-A of pod 152-A of network device 150,and may also be attachable to, pluggable into, or otherwise coupled(e.g., via one or more cables) to optical bus 170. In some examples,each port 152 of network device 150 may include a lane switch 155. Laneswitch 155 may be similar to lane switch 115, Accordingly, lane switch155 may convert and selectively route electrical signals from outputlanes L0 _(o)-L3 _(o) to optical outputs of connector 153 (and inputs ofmultiplexer 158), and convert and mute optical signals from inputs ofconnector 153 (and outputs of demultiplexer 157) to electrical signalsat input lanes L0 _(i)-L3 _(i).

In some examples, bus 170 may combine a plurality of optical signalsreceived from computing devices 110 through waveguides 171-A, 171-B,171-C, and 171-D into a single optical signal representing each of theplurality of optical signals. For example, bus 170 may use a pluralityof partially transparent mirrors 175 to combine signals carried bywaveguides 171-A, 171-B, 171-C, and 171-D into a single opticalwaveguide 181. Similarly, bus 170 may use partially transparent mirrors175 to replicate an optical signal (which may include a plurality ofoptical signals) received from module 154 through optical waveguide 182,and to deliver the optical signal to computing devices 110-A, 110-B,110-C, and 110-D by providing the optical signal into waveguides 172-A,172-B, 172-C, and 172-D, respectively. It is appreciated that in someexamples bus 170 may use components other than partially transparentmirrors to combine and/or replicate the optical signals.

In some examples, as illustrated in FIG. 2B, optical bus 170 may becoupled to module 154 via an optical cable, such as an LC duplex cable,that includes optical waveguides 181 and 182. In some examples, toreduce the total cable length, the optical cable connecting bus 170 andmodule 154 may be longer than the optical cables connecting computingdevices 110 to bus 170.

In some examples, as illustrated in FIG. 2C, computing devices 110(e.g., servers) may be included in an enclosure 105 (e.g., a serverrack) having an enclosure connector 114, which may, for example, besimilar to connector 153 discussed above. In these examples, eachcomputing devices 110 may be coupled via an optical cable, such as an LCduplex cable or other suitable optical cable, to enclosure connector114, and optical bus 170 may be attachable to, pluggable into, orotherwise coupled to enclosure connector 114.

In some examples, as illustrated in FIG. 2D, optical cables carryingwaveguides 181 and 182 (illustrated in FIG. 2A) may be omitted, andoptical bus 170 may be physically coupled to (e.g., attached or pluggedinto) module 154. In some examples, optical bus 170 and module 154 maybe integrated into the same module that may be attachable to orpluggable info connector 158 and that may be coupled to computingdevices 110, for example, through optical cables carrying waveguides 171and 172.

Referring back to FIG. 2A, network device 150 may generate an opticalsignal and send the optical signal (e.g., through pert 152-A connector153-A, multiplexer 156, and optical bus 170) to a plurality of computingdevices 110. In some examples, the optical signal may include aplurality of data signals and/or management signals, each signal beingassociated with a different wavelength. In some examples, the managementsignal may indicate which data signals are directed to which computingdevices 110. Put differently, the management signal may configure eachcomputing device 110 to discard some data signals, for example, byconfiguring lane switch 115 not to route those signals to input lanes L0_(i)-L3 _(i). In other examples, computing device 110 may be configuredto pass all data signals to input lanes L0 _(i)-L3 _(i) and to thendetermine which signals are directed to this computing device 110 basedon the signals themselves. For example, each computing device 110 mayanalyze the packet headers of the date signal, discard the packer if thepacket is a unicast packet directed to another computing device 110, andnot to discard the packet if the packet is a multicast packet or is aunicast packet directed to the present computing device 110.

As discussed above, the management signal may also indicate, to eachcomputing device 110, how many output signals, if any, the particularcomputing device 110 may transmit to network device 150 through bus 170.In some examples the management signal may also indicate the particularoutput lanes (L0 _(o)-L3 _(o)) from which the computing device 110 maytransmit the output signals; in other examples, computing device 110 maydetermine the particular lanes independently of the management signal.In some examples, the management signal may also indicate whichwavelength (e.g., from a plurality of predefined wavelengths such as λ1,λ2, λ3, and λ4) is to be associated with each such output signal; inother examples, the management signal may only indicate a set ofwavelengths, and computing device 110 may choose which output signalsare to be associated with which of the set of wavelengths. In someexamples, to avoid interferences between various output signals, themanagement signal may assign wavelengths to the various output signalsof various computing devices such that each output signal is associatedwith a different wavelength, i.e., no two output signals simultaneouslytransmitted through bus 170 to port 152 (e.g., 152-A) are associatedwith the same wavelength.

By using management signals to control which signals may be transmittedby which computing devices 110, network device 150 may control the totalbandwidth to be received from all computing devices 110, also referredto as the input bandwidth capacity, as well as the distribution of thatbandwidth among computing devices 110. In some examples, network device150 may determine the input bandwidth capacity based on the upstreamoutput bandwidth capacity. For example, if network device 150 may nottransmit to upstream devices more than 10 Gb/s (per port 152), networkdevice 150 may limit the amount of bandwidth to be received fromcomputing devices 110 by a given port 152 to up to 10 Gb/s. Networkdevice 150 may also use any suitable load-balancing algorithm todistribute the input bandwidth capacity among all computing devices 110connected to the given port 152. In some examples, the distribution maydepend at least in part on the individual bandwidth requirements of eachcomputing device 110, and may change with time, e.g., when theindividual requirements change. In some examples, for example, when thetotal bandwidth requirement of computing devices 110 exceeds the inputbandwidth capacity, network device 150 may use the management signal toindicate to each computing device 110 one or more time slots duringwhich that computing device 110 may or may not transmit data.

In some examples, a time slot may span a time period where one or morepackets can be sent between port 152 and a computing device 110. Theduration of a time slot may be selected by port 152. Port 152 may queryeach computing device 110 connected thereto with regard to its time slotneeds, and may instruct each computing device 110 when to start usingone or more time slots. Port 152 may also instruct each computing device110 to stop sending data, e.g., by issuing a stop command such as anEthernet flow-control PAUSE frame. In some examples, each computingdevice may request for one or more time slots from the network device.Each computing device 110 may send data to port 152 only during itsallotted time slot, and may prematurely relinquish its granted time slotby notifying port 152. Thus, in some examples, to accommodate varyingdownstream bandwidth requirements of a plurality of computing devices110, system 100 may selectively enable time-division multiplexing inaddition to wave-division multiplexing discussed above.

In the example illustrated in FIG. 3A. computing devices 110 areconfigured by the network device 150 as follows: device 110-A transmitsdata from output lane L0 _(o) using wavelength λ4, receives data usingwavelengths λ1-λ4, and passes to input lane L0 _(i) only data withwavelength λ3; device 110-B transmits data from output lane L0 _(o)using wavelength λ3, receives data using wavelengths λ1-λ4, end passesto input L0= only data with wavelength λ3; device 110-C transmits datafrom output lane L0 _(o) using wavelength λ2, receives data usingwavelengths λ1-λ4, and passes to input lane L0 _(i) only data withwavelength λ2; and device 110-D transmits data from output lane L0 _(o)using wavelength λ1, receives data using wavelengths λ1-λ4, and passesto input lane L0 _(i) only data with wavelength λ1. In this example ifeach lane L0-L3 of each com puling device 110 cars transmit at a rate of25 Gb/s, each computing device 110 can transmit and receive data at 25Gb/s, for a duration instructed by the network device 150.

In the example illustrated in FIG. 3B, computing devices 110 areconfigured by the network device 150 similarly to the way described inFIG. 3A, but each computing device 110 passes all data received fromnetwork device 150, leaving it to each computing device 110 to determine(e.g., based on the data itself) which of the data is directed to thatdevice. In this example, if each lane L0-L3 of each computing device 110can transmit at a rate of 25 Gb/s, each computing device 110 cantransmit data at 25 Gb/s and receive data at 100 Gb/s, for a durationinstructed by the network device 150.

In the example illustrated in FIG. 3C, computing devices 110 areconfigured similarly to the way described in FIG. 3B, but computingdevice 110-C is configured by the network device 150 not to transmit anydata to network device 150, while computing device 110-D is configuredto transmit both from output lane L0 _(o) using wavelength λ1 and fromoutput L1 _(o) using wavelength λ2. Thus, in this example, if each laneL0-L3 of each computing device 110 can transmit at a rate of 25 Gb/s,each computing device 110 can receive data at 100 Gb/s, devices 110-Aand 110-B can each transmit data at 25 Gb/s, device 110-C cannottransmit any data, and device 110-D can transmit data at a combined rateof 50 Gb/s, for a duration instructed by the network device 150.

In the example illustrated in FIG. 3D, computing devices 110 areconfigured by the network device 150 similarly to the way described inFIG. 3C, but computing devices 110-A, 110-B, and 110-C are configurednot to transmit any data to network device 150, while computing device110-D is configured to transmit both from output lanes L0 _(o), L1 _(o),L2 _(o), and L0 ₃ using wavelengths λ4, λ3, λ1, and λ2, respectively.Thus, in this example, if each lane L0-L3 of each computing device 110can transmit at a rate of 25 Gb/s each computing device 110 can receivedata at 100 Gb/s. devices 110-A, 110-B, and 110-C cannot transmit anydata, and device 110-D can transmit data at a combined rate of 100 Gb/s,for a duration instructed by the network device 150.

In the example shown in FIG. 3E, each computing device 110 may receiveand transmit through all lanes (e.g., at 100 Gb/s) but at different timeslots, after instructed by the network device 150, For example,computing devices 110-A, 110-B, 110-C, and 110-D may transmit duringtime slots T1-T2, T3-T4, T5-T6, and T7-T8, respectively.

In some examples, some or all functionality of any computing device 110may be implemented as any combination of hardware and programming. Theprogramming may include processor-executable instructions stored on atangible, non-transitory computer readable medium and the hardware mayinclude a processing resource for executing those instructions. Theprocessing resource, for example, may include one or multiple processors(e.g., central processing units (CPUs), semiconductor-basedmicroprocessors, graphics processing units (GPUs), field-programmablegate arrays (FPGAs) configured to retrieve and execute instructions, orother electronic circuitry), which may be integrated in a single deviceor distributed across devices. The computer readable medium can be saidto store program instructions that when executed by the processorresource implement the functionality of the respective component. Thecomputer readable medium may be integrated in the same device as theprocessor resource or it may be separate but accessible to that deviceand the processor resource. In one example, the program instructions canbe part of an installation package that when installed can be executedby the processor resource to implement the corresponding component inthis case, the computer readable medium may be a portable medium such asa CD, DVD, or flash drive or a memory maintained by a server from whichthe installation package can be downloaded and installed. In anotherexample, the program instructions may be part of an application orapplications already installed, and the computer readable medium mayinclude integrated memory such as a hard drive, solid state drive, orthe like.

FIG. 4 is a flowchart of an example method 400. Method 400 may bedescribed below as being executed or performed by a network device, suchas network device 150. Other suitable systems and/or computing devicesmay be used as well. Method 400 may be implemented in the form ofexecutable instructions stored on at least one non-transitorymachine-readable storage medium of the network device and executed by atleast one processor of the network device. Alternatively or in addition,method 400 may be implemented in the form of electronic circuitry (e.g.,hardware), in alternate examples of the present disclosure, one or moreor blocks of method 400 may be executed substantially concurrently or ina different order than shown in FIG. 4, in alternate examples of thepresent disclosure, method 400 may include more or less blocks than areshown in FIG. 4. In some examples, one or mora of the blocks of method400 may, at certain times, be ongoing and/or may repeat.

At block 410, method 400 may determine an input bandwidth capacity. Atblock 420, the method may, based on the input bandwidth capacity,generate, a management signal indicating an allowed number of signalsfor each of a plurality of computing devices coupled to a networkdevice. As discussed above, the management signal may also indicate awavelength to be associated with each of the allowed number of signalsof each of the plurality of computing devices, and in some examples, adifferent time slot for transmitting those signals. At block 430, themethod may send the management signal to the plurality of computingdevices through an optical bus. As discussed above, this may includesending to the plurality of computing devices an optical signal thatincludes the management signal and a plurality of data signals, wherethe data management signal and each of the plurality of data signals areassociated with a different wavelength. At block 440, the method mayreceive, through the optical bus, an optical signal corresponding to themanagement signal. As discussed above, the optical signal may include aplurality of input signals from the plurality of computing devices, andeach of the plurality of input signals may be associated with adifferent wavelength.

1. A computing device coupled to a network device port of a networkdevice vis a cable comprising a first optical waveguide and a secondoptical waveguide, wherein the computing device is to: obtain aplurality of output signals at a plurality of output lanes of thecomputing device; based on management data obtained from the networkdevice port through the first optical waveguide, select from theplurality of output signals a set of selected signals; using a laneswitch, selectively assign to each of the selected signals one of aplurality of predefined wavelengths in accordance with the managementdata; and provide to the network device port, through the second opticalwaveguide, an optical output signal representing each of the selectedsignals using the wavelength assigned to the selected signal.
 2. Thecomputing device of claim 1, wherein providing the optical output signalto the network device port comprises providing the optical output signalto an optical bus, wherein the optical bus is to combine the opticaloutput signal with a second optical signal received from a secondcomputing device through a third optical waveguide,
 3. The computingdevice of claim 1, wherein the computing device comprises a multiplexerhaving a data output and a plurality of data inputs, the data outputbeing optically coupled to the second optical waveguide, and each datainput of the multiplexer being associated with a different wavelength,wherein the multiplexer is to: obtain the plurality of output signals atthe plurality of data inputs of the multiplexer, each output-signalbeing associated with a different wavelength; select the set of selectedsignals from the plurality of output signals based on the managementdata; and provide the set of selected signals to the data output.
 4. Thecomputing device of claim 3, wherein the lane switch is to obtain theplurality of output signals from the plurality of output lanes,selectively assign to each output signal a different wavelength inaccordance with the management data, and route the plurality of outputsignals to the plurality of data inputs of the multiplexer in accordancewith the management data.
 5. The computing device of claim 1, furthercomprising a lane switch, wherein the lane switch is to: obtain anoptical input signal comprising a plurality of input signals from thenetwork device; extract the plurality of input signals from the opticalinput signal; and selectively route the plurality of input signals to aplurality of input lanes of the computing device.
 6. A network devicecomprising a network device port, the network device port being coupledto a plurality of computing devices via an optical bus, wherein thenetwork device is to: obtain, by the network port, a plurality ofelectrical output signals from the network device; produce, by thenetwork port, an optical output signal representing a management signaland the plurality of electrical output signals, wherein the managementsignal and the plurality of output signals are represented in theoptical output signal by different wavelengths, and wherein themanagement signal selects a set of output lanes from a plurality ofoutput lanes of each of the plurality of computing devices, and assignswavelength to each of the set of output lanes; provide, by the networkport, the optical output signal to each of the plurality of computingdevices through the optical bus; and receive, by the network port,through the optical bus, an optical input signal comprising, for eachcomputing device, a set of output signals from the set of output lanesselected by the management signal, each output signal being representedby a wavelengths assigned by the management signal.
 7. The networkdevice of claim 8, wherein the optical bus comprises at least onepartially-transparent mirror to replicate the optical output signal andat least one partially-transparent mirror to produce the optical inputsignal.
 8. The network device of claim 8, wherein the management signalis to control a plurality of optical multiplexers and a plurality oflane switches of the plurality of computing devices.
 9. The networkdevice of claim 8, wherein the management signal further indicates, forat least one of the plurality of computing device, a time slot duringwhich the at feast one of the plurality of computing device is allowedto transmit data to the network device port.
 10. The network device ofclaim 8, wherein the network device port is coupled to the optical busvia an optical multiplexor and an optical demultiplexer, wherein: theoptical multiplexer is to generate the optical output signal; and theoptical demultiplexer is to receive the optical input signal from theoptical bus, and extract a plurality of extracted optical signalsrepresenting the plurality of electrical input signals.
 11. The networkdevice of claim 10, wherein the network device port comprises aconnector attachable to an optical module comprising the opticalmultiplexer and the optical demultiplexer, wherein the optical module isone of: attachable to the optical bus, and coupled to the optical busvia an optical cable.
 12. A method comprising: determining an inputbandwidth capacity of a network device comprising a network device portcoupled to a plurality of computing devices; based on the inputbandwidth capacity generating a management signal the management signalindicating a set of output lanes for each of the plurality of computingdevices and indicating a different wavelength for each of the set ofoutput lanes of each of a plurality of computing devices; sending themanagement signal to the plurality of computing devices through anoptical bus; and receiving, through the optical bus, an optical signalcomprising, for each computing device, a set of output signals from theset of output lanes indicated by the management signal, each outputsignal being represented by a wavelength indicated by the managementsignal.
 13. The method of claim 12, wherein the network device port iscoupled to the optical bus via an attachable module comprising ademultiplexer to extract the plurality of input signals from the opticalsignal.
 14. The method of claim 12, wherein sending the managementsignal comprises sending to the plurality of computing devices anoptical signal comprising the management signal and a plurality of datasignals, wherein the data management signal and each of the plurality ofdata signals are associated with a different wavelength.
 15. The methodof claim 12, wherein the management signal further indicates, for eachof the plurality of computing devices, a different time slot fortransmission.